Airdale CPO

My Feedback: (3)

I have an CMPRO Extra 300 1.20 (red, white, blue with stars on the cowl and blue checker on the rudder) but I have no instructions for the CG. Now this A/C comes with a wing tube for both wing halves. I have gone online and used a CG calculator but I am not sure if the CG is right. No I have not flown this A/C due to I am not really sure of what the starting point sould be.

The center of my wing tube is 6 inches from the leading edge of the wing. I have always thought that the wing tube center would be the middle point of the CG. Obviously this is my first with split wings. When using these CG calculators, for 25% MAC its calling for 4.5-.6 inches back and at 33% it calls for 5.7-.8 inches back from the leading edge. I know that "a good starting point would be 25-33%" but I dont want it too nose heavy. Can you start an A/C with say 35-36% MAC?

Should I trust these calculators, or does anyone no anyone that has one of these to help me with the CG.

Thanks all!!

Brian

Ed Smith

Position of wing tubes have no relationship to C.G. They may be placed close to the C.G. for easy reference but not necessarily. A safe starting point for balancing the airplane is at 25% of the MAC. I emphasise starting point. The airplane may be slightly nose heavy but it will be controllable. A tail heavy airplane will not last very long. So set the C.G. initially at 25% of the MAC and then go through the whole trimming procedure to find the optimum C.G. position that suits your flying style.

Ed S

jeffk464

I balanced mine according to the instructions and plan to maiden today, so if all goes well I'll tell you how it went.

jeffk464

I just got back from my maiden and the balance point in the instructions was fine, although I was probably just slightly forward of it. The plane flies pretty decent but my engine has marginal power for it(super tiger 2300). I'm going to have to try a smaller prop and hopefully get some more power as it breaks in. I was getting just under 8000 rpm on a master screw 18x6 prop on 10% fuel.

Airdale CPO

My Feedback: (3)

jeffk464, do you have the same A/C that I do? What did your instructions state as far as the CG?

I have a MVVS 1.44 twin that I have installed and it will swing a 16x8. I hope that will be enough power as well. I think my A/C will weigh in at about 14lbs. If its not enough power then I plan on selling the MVVS and moving to a Moki or OS.

Brian

Airdale CPO

My Feedback: (3)

I have recalculated my CG with the online calculators and at 25% MAC the balance point is at 4.5 inches. When I put in 30% it falls out at 5.20 inches.

I consider myself a pretty good pilot but I am no expert (yet), so I will try and get out to the field this week and give it a shot. As soon as I pick up the aircraft at the 5.25 (30.5% MAC) inch mark it comes straight up with no tendency to tip forward or back. Now I just need to fuel and fly and test from there. I am still awaiting to see what jeffk464 states his instructions says on the model that he has.

Brian